Epigenetic therapy roadmap: loosening silenced genes → mutation-specific enzymes → editing the epigenome

Overview

1. 1980s-2006historic

   Silenced genes and the drugs that loosen them

   Baylin and others showed that abnormal DNA methylation silences tumour-suppressor genes as effectively as a mutation, and that the silencing can be reversed. Azacitidine, an old chemotherapy given at low dose, was approved for myelodysplastic syndromes in 2004 and shown to extend survival (AZA-001); decitabine followed. Vorinostat (2006) was the first HDAC inhibitor, loosening the packaging of DNA in cutaneous T-cell lymphoma.

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   Stephen B. BaylinEpigenetic reprogramming⟳Azacitidine⟳DecitabineHypomethylating agents (azacitidine, decitabine)Pierre Fenaux⟳VorinostatHistone deacetylases (HDAC)
2. 2009-2016historic

   The HDAC class finds its niche, and its limits

   Romidepsin and belinostat joined vorinostat in T-cell lymphomas, tucidinostat became China's first original epigenetic drug, and panobinostat was approved in myeloma in 2015 then withdrawn in 2021 when its confirmatory trial was not done. Broad HDAC inhibition proved too toxic and too unselective for solid tumours, which pushed the field towards enzymes that particular cancers depend on.

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3. 2017-2020current

   Mutation-specific epigenetic drugs

   Mutant IDH1 and IDH2 produce a metabolite that scrambles how genes are read; enasidenib (2017) and ivosidenib (2018) block the mutant enzymes, and AGILE showed ivosidenib plus azacitidine sharply extends survival in newly diagnosed IDH1-mutant AML. ClarIDHy brought ivosidenib to bile duct cancer. Tazemetostat (2020) was the first EZH2 inhibitor, for epithelioid sarcoma and follicular lymphoma, until Ipsen withdrew it worldwide in March 2026 over secondary blood cancers. For the first time an epigenetic drug had a molecular biomarker.

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4. 2020-2026current

   Hypomethylating agents as the backbone

   VIALE-A made azacitidine plus venetoclax the standard for older patients with AML who cannot have intensive chemotherapy, doubling remission rates; the hypomethylating agent primes the leukaemia for the BCL-2 inhibitor. Oral azacitidine maintenance and oral decitabine-cedazuridine took the class out of the infusion chair. Every new AML drug is now tested on top of this backbone.

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5. 2023-2026current

   Menin inhibitors and the first brain tumour epigenetic drug

   Certain leukaemias keep their genes switched on through a scaffold protein, menin. Revumenib (2024, AUGMENT-101) created the class for KMT2A-rearranged and NPM1-mutant acute leukaemias and ziftomenib (November 2025, KOMET-001) followed, both as once-daily pills; the resistance mutations in menin itself appeared within the first trials. Vorasidenib (INDIGO, 2023) became the first targeted therapy for IDH-mutant low-grade glioma, delaying radiation and chemotherapy by years.

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6. 2026-2030emerging

   Solid tumours and the transcriptional machinery

   Mevrometostat pairs EZH2 inhibition with enzalutamide in three phase 3 prostate trials (MEVPRO-1). PRMT5 inhibitors exploit the loss of MTAP in about a tenth of all tumours. Golcadomide degrades two lymphoma transcription factors and is in a first-line phase 3 (GOLSEEK-1). Degraders for the fusion transcription factors that drive childhood sarcomas, drugs for broken SWI/SNF complexes, NSD2 inhibitors and BET inhibitors are all in the clinic. Eprenetapopt's failure to refold mutant p53 is the reminder that a compelling mechanism is not a drug.

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7. 2030+speculative

   Writing to the epigenome

   Epigenetic editing uses a targeting protein fused to a methylation writer to switch a chosen gene off durably without cutting DNA; it is in first human trials outside oncology and its cancer use depends on solving tumour delivery. In the other direction, hypomethylating agents make tumours more visible to the immune system by re-expressing silenced antigens, an idea being tested in combination with checkpoint blockade. AI models trained on RNA data are hunting drugs against transcription factors directly.

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8. What sets the pacecurrent

   Undruggable targets, plasticity and biomarkers

   Many epigenetic regulators have no pocket for a small molecule, which is why degraders and glues matter here more than anywhere. The same plasticity the drugs exploit lets tumours change state to escape them. And because the mechanism is not a mutation, finding the patients who will respond is harder: methylation profiling and expression signatures, not gene panels, are the likely biomarkers.

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   The undruggable driversAcquired resistance to every therapyTumour heterogeneity and clonal evolutionBiomarkers are not validated or standardisedPROTACs & molecular glues (targeted protein degradation)DNA methylation profiling

Every era's records, trial outcomes and papers, and every watch item, as JSON.